Peptide Reconstitution Calculator
Work out the concentration after mixing, then the volume and U-100 syringe units for the dose you want to draw.
The total milligrams printed on the vial, before any water is added.
How much liquid you mixed into the vial. More water means a weaker concentration and a larger volume per dose.
Enter the dose you have been prescribed. 1000 mcg equals 1 mg.
If you choose a size, we check the dose fits on that syringe.
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What reconstitution actually does
How mixing changes the concentration
A vial of peptide is a dry powder. Until you add liquid there is no concentration to measure — only a total amount in milligrams. Adding bacteriostatic water is what turns that powder into something you can draw into a syringe.
The water you add decides the strength
The same 5 mg vial becomes 5 mg/mL with 1 mL of water, or 2.5 mg/mL with 2 mL. The amount of peptide has not changed. What changes is how much liquid carries each dose — and therefore how far up the syringe you draw.
A worked example
Put 2 mL of bacteriostatic water into a 5 mg vial and the concentration is 2.5 mg/mL. A 250 mcg dose is 0.1 mL, which is the 10-unit mark on a U-100 syringe. Use 1 mL of water instead and the same 250 mcg dose sits at the 5-unit mark, because the liquid is twice as strong.
Why smaller volumes are harder to measure
A strong concentration means a very small volume per dose, and small volumes are harder to draw accurately. That is the trade-off: more water is easier to measure but fills the vial faster. The calculator shows the syringe units either way, and flags a dose that will not fit on the syringe you pick.
The basics
Milligrams, milliliters and syringe markings explained
mg
mg tells you how much medication
Your prescribed dose is the amount of medication you take, measured in milligrams.
mL
mL tells you how much liquid
The calculator determines the liquid volume corresponding to your prescribed dose using the concentration you enter.
mg/mL
Concentration connects the two
Concentration tells you how many milligrams are in a given volume of liquid. A more concentrated solution contains more medication in each mL, so the same prescribed dose requires less liquid.
units
Syringe markings measure that liquid
On a U-100 insulin syringe, 100 units equals 1 mL and 50 units equals 0.5 mL. These markings measure volume, not milligrams of medication.
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